High tension electric fuse



April 3, 1934. LE ROY H. Hol-FER HIGH TENSION ELECTRIC FUSE Filed Aug. 20, 1930 NVENTOR Epof/ f/OFFEK.

ATTORNEYS Patented Apr. 3, 1934 UNITED STATES PATEN'Il OFFICE HIGH TENSION ELECTRIC FUSE Application August 20, 1930, Serial No. 476,532

11 Claims.

This invention relates to electric fuse apparatus and more particularly to improvements in fuse apparatus of the type shown in Murray Patent No. 1,740,699 and in other patents, in which one end of a fuse element or fuse wire is carried in a movable head or plunger in a casing in such a manner as to be rapidly and forcibly expelled from the casing upon the blowing of the fuse and to carry with it the end of the fuse wire, and to f thus prevent or break an arc between the adjacent burnt ends of the wire.

In fuse apparatus of the above type the plunger carrying the end of the burnt fuse wire is expelled from its casing with extreme sudden- 15 ness and with explosive force, so that the ends of the fuse wire become instantly separated to too great a distance to permit the formation or maintenance of an arc. To permit of this Wide separation with certainty and safety requires apparatus of considerable size and strength.

An object of the present invention is to provide a strong and compact apparatus of the above type in which the avoidance or extinction of an arc may be accomplished with certainty and safety in a limited space, and to provide a casing, for a fuse of the above type, of maximum strength and one that may be readily taken apart for removal or replacement of fuse parts.

Other objects of the invention will appear more fully from the following description of the invention.

The Various features of the invention are illustrated in the accompanying drawing in which Fig. 1 is a vertical sectional view of a fuse apparatus embodying a preferred form of the invention,

Fig. 2 is a sectional view taken on line 2-2 of Fig. 1, and

Fig. 3 is a sectional view taken on the line 3 3 of Fig. 1.

In the present invention the fuse is enclosed in a strong stress-resisting container having, preferably in its lowermost part, a body of an insulating iiuid such as a heavy non-volatile mineral oil, and the fuse is so mounted in the container that its open end, through which the plunger and the burnt end of the fuse wire is projected, is directed into or towards the body of insulating fluid. One end of the fuse wire is connected to an electric terminal or binding post, preferably located in the body of oil or insulating fluid, through the upper closed part of the fuse casing. The opposite end of the fuse wire extends through the plug or plunger in the casing and thence through the open 55 end of the fuse' casing to a second terminal, also preferably extending into the body of insulating fluid.

The connection of this second terminal to the fuse wire is such that when the plunger is expelled it becomes submerged in and remains in *30 the body of insulating fluid and such that the oil or insulating iluid eiectively seals the expelled plunger and its fuse wire and terminal from any connection with the opposite end of the fuse wire and its terminal.

Referring more particularly to the accompanying drawing, the body of insulating fluid 10 is contained within metallic cup or reservoir 11, having an insulating inner lining 12 and iills the reservoir to the level A above the lower end of the casing 15. 'I'he fuse wire 13 is secured at its upper end in a stationary plug 14 in a fuse casing 15. A slidable plunger 16 is also mounted in the fuse casing 15 at a short space below the plug 14, and the fuse wire 13 is narrowed or restricted in cross-section at the point 17 between the plunger 16 and the plug 14, so that the fuse will blow between the plunger 16 and the plug 14 and expel the former into the oil body 10.

The fuse casing 15, which is of insulating material, is supported Within a metallic fuse container 18, having at its lower end a iiange 19 by which it is supported on and secured to the lower container 11 by means of a clamping nut or collar 20. The upper end of the fuse container 18 is closed by a metal cup 21 that is threaded on the upper end of the fuse container.

The fuse container 18 is lined with a pair of cylindrical layers of insulating material 22 and 23, and the cap 21 is lined with a disc 24 of insulating material. The space between the insulating lining 12 and the cylindrical layers 22 and 23 is spanned by a pair of insulating discs or washers 25 and 26, so that all of the metal parts above the surface of the oil body 10 are lined with insulating material.

The upper end of the fuse wire 13 is connected into an electric circuit by means of a copper conductor 27 that extends from the upper end of the plug 14, in contact with the upper end of the fuse wire 13, between the upper edges of the insulating cylinders 22 and 23 and the plate 24, thence between the cylinders 22 and 23 and the discs 25 and 26 to a copper connecting piece 28 and to a terminal 29 extending through an insulator from the container 11. The conductor 27 may be flat in its upper portion and circular in its lower portion or of other shape to t the apparatus. The portion of the conductor 27 extending from the disc 26 to the copper connecting piece 28 is insulated and the copper piece 28 is also contained in a body 30 of insulating material.

The lower end of the fuse wire 13 is connected by a flexible connector 31 through the open end of the fuse casing 15 to the upper end of an insulated connecting wire 32 which extends downwardly into the body of oil 10 and is connected to an insulated terminal 33 by means of a connecting mass 34 which is enclosed in a body 35 of insulating material in the bottom of the oil container 11.

When the fuse wire is subjected to an abnormal current it blows at the point 17 and immediately expels the plunger 16 through the open end of the fuse casing'15 and into the body of oil 10. As indicated in Fig. 1 of the drawing the lower end of the fuse casing 15 may project into the body of oil 16 so that the latter seals the inner part of the casing from the outer part. The expulsion of the plunger 16, and with it the burnt end of the fuse wire 17, is instantaneous, thus providing adverse conditions for the formaJ tion or maintenance of an arc. The forcible expulsion of the plunger also immediately sub- 'merges it in the body of oil 10 which acts to immediately quench any arc that may have been formed. The body of oil also serves to receive and deaden the impact of the plunger.

The gases that may be formed in the blowing 'of the fuse may escape from the upper part of fthe container 11, above the surface of the oil body 10 through an outlet 35' to a tank 36 that is filled with water into which the end of the tube :35 projects.

After a fuse has been blown it may be re- "moved and replaced by removing the connecting nut or ring 20 and the cap 21. A thumbscrew 37 that serves to retain the fuse casing 15 in the (fuse container may then be loosened to permit 'the withdrawal of the fuse casing.

Through the above invention a fuse of the plunger type, capable of handling large currents may be mounted in a relatively small space in a compact arrangement and provide a safe and certain extinction of any arcs that may be formed by the blowing of the fuse. The usefulness and capabilities of a fuse of this type are therefore greatly increased.

I claim:

1. A fuse comprising a body of insulating liquid, a fuse wire casing above said body of insulating liquid closed at its upper end and having an open lower end, a fuse wire in the upper end of said casing, a flexible connectiontherefrom extending through the open end of said casing' and through said insulating liquid, and a freely slidable plug in the upper part of said casing below .the blowing point of said fuse wire and above the liquid surface therein.

2. A fuse comprising a body of insulating liquid, a fuse wire casing above said body of insulating liquid closed at its upper end and having an open lower end dipping into said body of insulating liquid, a fuse wire in the upper end of said casing, a flexible connection therefrom extending through the open end of said casingand a freely slidable plug in the upper part of said casing below the blowing point of said fuse wire and above the liquid surface therein.

3. A fuse comprising a body of insulating liquid. a fuse wire casing above said body of insulating liquid closed at its upper end and having an open lower end, a fuse wire in the upper part of said casing, terminals in said insulating liquid, insulated conductors from said terminals, one to said fuse wire within said casing and the other having a flexible connection to said fuse wire through the open end of said casing, and a plug in the upper end of said casing below the blowing point of said fuse wire and secured to said fuse wire.

4. A fuse comprising a body of insulating liquid, a fuse wire casing above said body of insulating liquid, said casing being closed at its upper end and having a lower end projecting toward said body of insulating liquid, a slidable plunger in. said casing above the liquid surface therein, a fuse wire in said casing extending through and embedded in said plunger, and means for removably supporting said casing above said body of insulating liquid.

5. A fuse comprising a body of insulating liquid, a fuse wire casing having an open lower end projecting into said body of insulating liquid, a slidable plunger in said fuse wire casing above the liquid surface therein, a fuse wire in said casing and extendingthrough and secured in said movable plunger, and a iiexible connection to said fuse wire through the open end of said fuse wire casing and through said body of insulating liquid.

6. A fuse comprising a body of insulating liquid, a fuse wire casing having an open lower end projecting into said body of insulating liquid, a slidable plunger in said fuse wire casing spaced above the surface of insulating liquid therein, a fuse wire extending in said casing through and secured in said slidable plunger and having a blowing point above said plunger, and a connection to said fuse wire below said plunger and through the open end of said fuse wire casing and through said body of insulating liquid.

7. A fuse comprising a body of insulating liquid, a fuse wire casing having an open end projecting toward said body of insulating liquid, a slidable plunger in said fuse wire casing above the surface of liquid therein, a fuse wire in said casing and extending through and secured in said movable plunger, and a flexible connection to said fuse wire through the open end of said fuse wire casing and through said body of insulating liquid, a metallic chamber enclosing said body of insulating liquid and said fuse casing and having an insulating lining.

8. A fuse comprising a body of insulating liquid, a fuse wire casing having an open end projecting toward said body of insulating liquid, a freely slidable plunger in said fuse wire casing above the surface of liquid therein, a fuse wire in said casing and extending through and secured in said movable plunger, and a exible connection to said fuse wire through the open end of said fuse wire casing and through said body of insulating liquid, a metallic chamber enclosing said body of insulating liquid and said fuse casing and having insulator lining, and an exhaust outlet from said chamber above the surface of said body of insulating liquid.

9. A fuse comprising a fuse wire, a casing of considerable length enclosing said fuse wire and having an open end, a freely slidable plunger at a distance from said open end, said fuse element having a fusing point at the inner side of said movable plunger, a body of insulating liquid closing the open end of said casing and a flexible connection to said fuse wire through the open end of said casing and through said insulating liquid.

10. A fuse comprising an upright tube, a fixed barrier in the upper part of said tube, said tube having its lower end open, a movable plunger in the upper part of said tube beneath said fixed voir, a plunger in the upper part of said casing, means for removably securing said fuse Wire casing in said fuse container, a fuse wire in said fuse wire casing above said plunger and means connecting said fuse wire to said plunger through the open end of said casing, said plunger being spaced a substantial distance above the open end of said casing.

LE ROY H. HOFFER. 

